odin-javascript-exercises/node_modules/eslint/lib/rules/prefer-numeric-literals.js
2017-12-15 12:56:14 -06:00

112 lines
3.6 KiB
JavaScript

/**
* @fileoverview Rule to disallow `parseInt()` in favor of binary, octal, and hexadecimal literals
* @author Annie Zhang, Henry Zhu
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Checks to see if a CallExpression's callee node is `parseInt` or
* `Number.parseInt`.
* @param {ASTNode} calleeNode The callee node to evaluate.
* @returns {boolean} True if the callee is `parseInt` or `Number.parseInt`,
* false otherwise.
*/
function isParseInt(calleeNode) {
switch (calleeNode.type) {
case "Identifier":
return calleeNode.name === "parseInt";
case "MemberExpression":
return calleeNode.object.type === "Identifier" &&
calleeNode.object.name === "Number" &&
calleeNode.property.type === "Identifier" &&
calleeNode.property.name === "parseInt";
// no default
}
return false;
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
docs: {
description: "disallow `parseInt()` and `Number.parseInt()` in favor of binary, octal, and hexadecimal literals",
category: "ECMAScript 6",
recommended: false
},
schema: [],
fixable: "code"
},
create(context) {
const sourceCode = context.getSourceCode();
const radixMap = {
2: "binary",
8: "octal",
16: "hexadecimal"
};
const prefixMap = {
2: "0b",
8: "0o",
16: "0x"
};
//----------------------------------------------------------------------
// Public
//----------------------------------------------------------------------
return {
CallExpression(node) {
// doesn't check parseInt() if it doesn't have a radix argument
if (node.arguments.length !== 2) {
return;
}
// only error if the radix is 2, 8, or 16
const radixName = radixMap[node.arguments[1].value];
if (isParseInt(node.callee) &&
radixName &&
node.arguments[0].type === "Literal"
) {
context.report({
node,
message: "Use {{radixName}} literals instead of {{functionName}}().",
data: {
radixName,
functionName: sourceCode.getText(node.callee)
},
fix(fixer) {
const newPrefix = prefixMap[node.arguments[1].value];
if (+(newPrefix + node.arguments[0].value) !== parseInt(node.arguments[0].value, node.arguments[1].value)) {
/*
* If the newly-produced literal would be invalid, (e.g. 0b1234),
* or it would yield an incorrect parseInt result for some other reason, don't make a fix.
*/
return null;
}
return fixer.replaceText(node, prefixMap[node.arguments[1].value] + node.arguments[0].value);
}
});
}
}
};
}
};